This invention relates generally to the field of controls and control systems for use with controlled systems or other utilization devices, and more particularly to such controls and control systems wherein an information signal is generated responsive to movement of a moveable element and which movement is productive of an associated interactive tactually perceivable response.
Broadly speaking, controllable apparatus or more generally utilization devices have long required the capability to interact with a managing element in connection with the operation performed by the managing element. This interfacing capability has required the flow of information in both directions: as status indications from the controllable apparatus or utilization device to the managing element, generally hereinafter referred to as an output operation; and conversely from the managing element to the controllable apparatus, generally hereinafter referred to as an input operation. In the following discussion, input and output will be with reference to the electrical system.
In dealing with controllable apparatus the managing element can take numerous forms. Frequently the managing element is a human operator who reacts accordingly to status indications from the controllable apparatus. However managing elements can assume other forms, such as automated systems including electro-mechanically controlled implements for effecting operations with respect to one or more selected parameters of movement. In this application, "operator" is used to mean any managing element, such as a human operator or electro-mechanically controlled implement or the like, that interacts with the controllable apparatus. Such systems of necessity must include an interface between the controllable apparatus and the operator which permits the efficient flow of information in both input and output operations. In the broad area of input operation, this frequently includes a displacement device having a moveable portion with a parameter of movement associated therewith. Such parameters of movement can include physical motion of either a translatory or rotational nature, e.g., the translatory or rotational movement of a single or multiple position switch, potentiometer, etc. Likewise, in the broad area of output operations, efficient flow of information requires that the information from the controllable apparatus be in a format perceivable by the operator. The formatting of such information often involves a plurality of relations involving the visual, auditory or tactile senses. Well known devices useful for the flow of output information to the visual senses are various light indicator devices including light emitting diodes and cathode ray tubes; and to the auditory senses, conventional loud speakers employing permanent magnetics and voice coils, and more recently solid state sounding devices. Tactually perceivable sensations have not been used in a dynamically interactive manner. The use of the tactile sense has been restricted to a static interaction, for example, for perception of fixed detents and/or a constant drag in devices executing translatory or rotational motion; e.g., rotational devices having a fixed drag or a fixed number of detents for indication of position.
As technology has continued to expand, controlled systems have likewise continued to expand in complexity, sophistication, and the scope of the general work or task implemented or controlled. Simultaneously with the growth in the complexity and sophistication of the controlled system has been a corresponding increase in the associated quantity of input and output information. For human operators of such systems, this has often resulted in a staggering collection of switches, knobs and indicating devices with which to deal, each frequently dedicated to control a unique parameter of the controlled system. As the basic requirement underlying all such arrays of switches, knobs and indicating devices is the bi-directional flow of information between an operator and the controlled system, a problem is often encountered. This problem relates particularly to the human limitation that only a finite amount of information can be effectively dealt with at any one time. This includes not only the basic information which may be flowing in either an input or output sense, but also the human requirement that certain physical parameters such as switch or indicator location on a panel as well as the corresponding information associated therewith must be simultaneously considered by the operator for an intelligent, desired operation to result. This requirement is particularly significant in areas where the associated desired operator response is either a rapid one or one of a creative nature.
Such requirements have frequently resulted in multifunctional inputs or output devices, such as switches or knobs whose functions can be changed in a dynamic manner in response to changing requirements, or indicating devices such as cathode ray tubes on which the display thereon can be quickly changed. In terms of the art, such devices are referred to as "soft", e.g., soft switches, to indicate that the associated functions can be changed at will.
A particular example of multifunctional use of a push button is observed with the so called "soft keys" which are frequently encountered on the typewriter type keyboard generally found with a computer terminal. The function of such keyboard keys can be generally assigned to any of a multitude of functions depending upon the particular application; such functions can thereafter be changed as easily as entering new data on the computer terminal.
While switches involving translatory motion whose functions can be changed at will are well known and widely used, input devices involving rotational motion whose function can be easily changed have not seemed to have found equal wide spread use.
With the growth of the use of microprocessors, digital processing of information is becoming increasingly widespread. Applications previously considered as distinctly analog in nature are now being processed in a digital manner, with the corresponding use of analog-to-digital converters to transform the analog information of interest to a digital format for the requisite digital processing, and the subsequent conversion of the results, in a digital format back to an analog format, for interaction with the particular environment. In such an environment where information is converted from a continuous analog nature to a discrete digital nature, it is desirable for input devices from the external world to provide information directly in a digital rather than analog format. Input devices capable of providing basic input information in a digital or binary form frequently represent translatory physical motion, such as the depressing of a switch or key. The corresponding output generally assumes one of the well known conventional forms susceptible to perception by the operator's visual or auditory sense.
In comparison with input devices involving translatory motion, there has been relatively few input devices involving rotational motion available. In the past, such devices were frequently limited to potentiometers which directly produced an output in an analog format. Consequently in using such a device for input purposes, a number of problems were present. To effectively use the output of a potentiometer which produces output in an analog format, an analog-to-digital conversion process is essential. An additional problem relates to the fact that the analog signal produced is unalterably associated with a fixed angular position; i.e., if a potentiometer were going to be used as an input device, the angular reference point, e.g., the zero reference position, always remains at the same angular position. This severely limits the usefulness of the device as an input means to a digital system.
A solution to the problem presented by the nature of the output signal produced by a potentiometer is afforded by the use of a tachometer. In particular, a slotted disc is attached to a rotatable shaft, with a light source positioned on one side of the slotted disc, and a light sensing means positioned on the opposite side of the disc, in alignment with the light source. Consequently, as the shaft is rotated, the beam of the light is interrupted by the rotating disc, thereby producing an output signal, usually of a binary nature. By appropriate decoding means, both amount of rotation as well as speed of rotation are ascertainable. It is further observed that by use of a second set of slots on the disc, distinct and separate from the first set, but displaced from the first set by an appropriate amount along with a second light sensing means and an optional second light source, information indicative of direction of rotation of the shaft is also produced.
In particular, an input device incorporating a tachometer, while being able to provide input information, still suffers from a number of short comings. In particular, such an input device, while being capable of providing information based upon rotational motion, would generally lack end stops, i.e., means to limit the extremeties of angular rotation.
Likewise, such an input device would lack detents at selected angular positions. This feature, which is commonly found on analog potentiometers is often quite useful in either presetting the input device to a known value or use as a reference point in the operation of the knob. However, by so providing fixed detents on the above described input device, a similar limitation in the flexibility results.
Furthermore, such an input device as above described incorporating a knob coupled to a tachometer by a shaft would have a fixed rotational friction or drag associated with rotation. In analog potentiometers, the amount of drag is frequently mechanically selectable, depending upon the particular device selected and the manner in which it is physically mounted. Such flexibility is clearly lacking in the above described input device. However, rotational friction or drag could be effected by mechanical adjustments on the shaft coupling the knob to the tachometer, or by other means, such would again limit the flexibility of resulting device.